#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
#       pipeline.maxpy
#
#  This file is part of the MaxTrader Project. http://www.maxtraderbd.com/
#
#  Copyright (c) 2011 invarBrass, MaxTrader Software Services <info@maxtraderbd.com>
#  
#  All rights reserved.
#
#  Redistribution and use in source and binary forms, with or without
#  modification, are permitted provided that the following conditions are met:
#      * Redistributions of source code must retain the above copyright
#        notice, this list of conditions and the following disclaimer.
#      * Redistributions in binary form must reproduce the above copyright
#        notice, this list of conditions and the following disclaimer in the
#        documentation and/or other materials provided with the distribution.
#      * Neither the name of the MaxTrader Software Services nor the
#        names of its contributors may be used to endorse or promote products
#        derived from this software without specific prior written permission.
#
#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
#  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
#  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
#  DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
#  DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
#  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
#  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
#  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
#  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
#  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
# $Author: masroore@gmail.com $
# $Id: pipeline.py 22 2011-10-01 15:33:48Z masroore@gmail.com $
# $Rev: 22 $

class PipelineContext(object):
    _errors = []
    
    def get_errors(self):
        return self._errors
    
    def has_errors(self):
        return True if len(self._errors) > 0 else False
    
    def add_error(self, err):
        self._errors.append(err)
        
    def error_messages(self):
        return '\r\n'.join(self._errors)
    
class Stage(object):
    def execute(self, context): abstract
    
class Pipeline(Stage):
    def add_stage(self, stage): abstract
    
class SequentialPipeline(Pipeline):
    _stages = []
    
    def add_stage(self, stage):
        self._stages.append(stage)
        
    def execute(self, context):
        for stage in self._stages:
            stage.execute(context)